Script or action program to automate Photoshop inserting of image onto template

We are looking for a script or ready made program to assist with creation of t shirt templates. Basically we have an transparent image which we then manually place onto a t shirt template and then save. Now I know we can do an action for this but its clunky and can breakdown and also complicated. Basically we have 15 coloured t shirt templates, 6 coloured ladies templates and 10 coloured hoody templates. We need an easy way to mass process a batch of images onto t shirts or whatever. They will need to be automatically resized and placed in a specific area on the shirt or hoody. We have thousands of images so a nice easy GUI or program would be great. If not something robust that latches onto photoshop would be ok. Any questions just let me know We use apple macs as well so must be compatible. A fast turnaround is a must for this.